Using touch inputs through raycasts to drive animations.

I want to create a similar Augmented reality experience similar to Hienz AR.I have modeled and animated the book in 3Ds max. I have imported them as fbx file. I have created two quads and used a png texture as cutout material on the quad making the quad look like a button that would drive the book flip thus "next (button) and back (button)". I have set up vuforia and everything that would drive the augmentation. I have no idea of how to script touch inputs that would raycast on the quads thus (next and back) to drive the animation of the book flipping backwards and forwards.